Specifications Electronic:No High-concerned chemical:None Type:Heating Type Repeatability:4 Wires Measuring Range:4Pcs Sensitivity:Lambda O2 Oxygen Sensor Sensor Type:Piezoelectric Origin:Mainland China OEM NO.:234-4256 234-4668 Resolution:Oxygen Sensor car model 1:For Cadillac Escalade Chevrolet Silverado Suburban Tahoe GMC Sierra Replaces OEM Part Number: 234-4256 234-4668 Fit : for 2009-2013 Cadillac Escalade V8-6.0 2 Upsteam & 2 Downstream for 2008-2014 Cadillac Escalade V8-6.2 2 Upsteam & 2 Downstream for 2008-2014 Cadillac Escalade ESV V8-6.2 2 Upsteam & 2 Downstream for 2008-2013 Cadillac Escalade EXT V8-6.2 2 Upsteam & 2 Downstream for 2008-2013 Chevrolet Avalanche V8-5.3 2 Upsteam & 2 Downstream for 2008-2009 Chevrolet Avalanche V8-6.0 2 Upsteam & 2 Downstream for 2008-2013 Chevrolet Silverado 1500 V8-4.8 2 Upsteam & 2 Downstream for 2008-2013 Chevrolet Silverado 1500 V8-5.3 2 Upsteam & 2 Downstream for 2008-2013 Chevrolet Silverado 1500 V8-6.0 2 Upsteam & 2 Downstream for 2009-2013 Chevrolet Silverado 1500 V8-6.2 2 Upsteam & 2 Downstream for 2008-2011 Chevrolet Silverado 2500 HD V8-6.0 Pickup ;2 Upsteam & 2 Downstream for 2008-2011 Chevrolet Silverado 3500 HD V8-6.0 Pickup ;2 Upsteam & 2 Downstream for 2008-2014 Chevrolet Suburban 1500 V8-5.3 2 Upsteam & 2 Downstream for 2008-2009 Chevrolet Suburban 1500 V8-6.0 2 Upsteam & 2 Downstream for 2013 Chevrolet Suburban 2500 V8-6.0 2 Upsteam & 2 Downstream for 2008-2011 Chevrolet Suburban 2500 V8-6.0 2 Upsteam & 2 Downstream for 2008-2009 Chevrolet Tahoe V8-4.8 2 Upsteam & 2 Downstream for 2008-2014 Chevrolet Tahoe V8-5.3 2 Upsteam & 2 Downstream for 2008-2013 Chevrolet Tahoe V8-6.0 2 Upsteam & 2 Downstream for 2008-2009 Chevrolet Tahoe V8-6.2 2 Upsteam & 2 Downstream for 2008-2013 GMC Sierra 1500 V8-4.8 2 Upsteam & 2 Downstream for 2008-2013 GMC Sierra 1500 V8-5.3 2 Upsteam & 2 Downstream for 2008-2013 GMC Sierra 1500 V8-6.0 2 Upsteam & 2 Downstream for 2008-2013 GMC Sierra 1500 V8-6.2 2 Upsteam & 2 Downstream for 2008-2011 GMC Sierra 2500 HD V8-6.0 Pickup ;2 Upsteam & 2 Downstream for 2008-2011 GMC Sierra 3500 HD V8-6.0 Pickup ;2 Upsteam & 2 Downstream for 2008-2009 GMC Yukon V8-4.8 2 Upsteam & 2 Downstream for 2008-2014 GMC Yukon V8-5.3 2 Upsteam & 2 Downstream for 2008-2013 GMC Yukon V8-6.0 2 Upsteam & 2 Downstream for 2008-2014 GMC Yukon V8-6.2 2 Upsteam & 2 Downstream for 2008-2014 GMC Yukon XL 1500 V8-5.3 2 Upsteam & 2 Downstream for 2008-2009 GMC Yukon XL 1500 V8-6.0 2 Upsteam & 2 Downstream for 2008-2014 GMC Yukon XL 1500 V8-6.2 2 Upsteam & 2 Downstream for 2008-2013 GMC Yukon XL 2500 V8-6.0 2 Upsteam & 2 Downstream More adapter models please ask customer service Package included: 4 * Oxygen Sensor Note: 1. Please check OEM number before purchasing. 2. Please allow 1-3cm error due to manual measurement. Thanks for your understanding. 3. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard. Must Know Before Buying: A: The only way to know if the O2 sensor is functioning normally is to check its responsiveness to changes in the air/fuel mixture, by Voltage Measurement or Waveform Simulation. Use a 10-megaohm digital voltmeter. Hook up the voltmeter's red probe to the sensor's signal wire and the black probe to engine ground. (Use back probe method, DO NOT pierce the wire.) For a good sensor, voltage should fluctuate constantly between 0.1 and 0.9 volts after starting the engine for 2 or 3 minutes. Please take a video clip of the voltmeter and contact us if our sensor: Goes above range between 0.1 and 0.9 volt Remains below 0.5 volts Stays fixed at a particular voltage You're free to choose replacement or refund if our sensor fails to work, in this case. Position confirmation: Upstream sensor is before the catalytic(cat.) converter. Downstream sensor is after the catalytic converter. Upstream oxygen sensor is also known as sensor 1, or pre-cat, or upper oxygen sensor. Downstream oxygen sensor is also known as sensor 2, or post-cat, or lower oxygen sensor. When should we replace the oxygen sensor : How to replace the oxygen sensor : Step 1 - Some sensors are equipped with a heat shield that must be removed before the sensor removal, this is performed by removing any mounting bolts. Step 2 - By using a regular socket it minimizes potential damage to the sensor body and the threads, this technique helps avoid stripping the old sensor upon removal. Step 3 - Then, locate and disconnect the wiring connector, this step should be done before removing the sensor if the wiring is still attached. Step 4 - Its important that the wiring harness connectors are exactly the same, each sensor i